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H. GEISENH GNER.

METAL HEATING DEVICE. APPLICATION FILED APR-26.1918.

Patented Dec. 2, 1919.

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Hind 4'0 K In Ventor: Henry Geisenhner,

His 'fictorneg.

UNITED STATES PATENT OFFICE.

HENRY GEISENHQNER, OF SCHE'NEGTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC CDMPANY, A CORPORATION OF NEW YORK.

METAL-HEATING DEVICE.

To all whom it may concern:

Be it known that I, HENRY Ge sizxuoxnn, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Metal Heatin Devices, of which the following is v a specification.

The present invention relates to the heating of elongated metal objects, such, for example, as bolts, rivets or any other metal parts to be heated and comprises botha novel method of heating and a novel apparatus for carrying out this method.

When bolts, rivets, bars or similar elongated metal objects are heated by the passage of current through the object, the electrodes being applied at each end, the objects are apt to be overheated at the contact unheated object, each object usually being in a difi'erent phase of heat treatment, or at a difi'erent temperature. My invention also includes a heating apparatus hereinafter more fully described for carrying out this process.

The accompanying drawing illustrates one form of apparatus embodying my invention, Figure 1 being a side elevation; Fig. 2 is a horizontal section taken on lines '2-2; Fig. 3 is a longitudinal section of.

part 'of the welding apparatus taken on lines 33 of Fig. 2; Figs. 4 and 5 illustrate a heat radiator for the electrode; Fig. 6 is a diagram of electrical connections.

Referring to Fig. 1, the apparatus illustrated comprises a frame mnstitutcd by uprights 5, 6 consisting conveniently of channel ll0Ii-, provided with an insulating base 7, and provided with a plurality oi transverse supports 8, 9, 10 and 11,- boltcdto the channel irons. These supports may consist of asbestos board, or other. suitable insulatin material. Resting on the insulatingbase is an electrode 12 andspaced above Specification of Letters Patent.

Application filed April 26, 1918. Serial No. 230.949.

the same substantially equal distances are electrodes 13, 1-}, l5 and 16. each of the electrodes 1Il1(i being pivotally supported on the channel iron frame. As shown in Fig. :2, these electrodes 1316 are carried by rods 17 held in place at each end by nuts 18 and 19, and surrounded by an insulating sleeve 20 consisting, for example, of fiber tube, to prevent the electrodes being short circuited by the channel irons. As shown best in Figs. 2 and 3, each of the electrodes 13-1(3 is fastened to one end of a frame consisting of bars 21, '22, through which the insulated rod 17 passes. At the end of the frame opposite the electrodes is fastened a counterweight attached to the bars 21. 22, by a rod 24, provided at each end with a nut 25. Each of the electrodes 12 to 16 is preferably made hollow, as shown in Fig. 3 and cooled by circulation of water, or other suitable fluid, supplied by tubes 26. These tubes may be supplied with cooling liquid in any suitable way but conveniently they may be connected by conduits 27, 28, to a radiator 29, as shown in Fig. 1.

In some cases theelectrodes 12 to 16 can be sufficiently cooled by a circulation of air and for that purpose are provided with heatdissipating flanges, onfins 30, as shown in Figs. 4 and These air'cooled radiators may conveniently be provided with slots 31 into which may be hung rivets 32, which are in this manner pre-heated to some extent and may be removed by, theworkmen and inserted in the rivet heating machine, cold objects being substituted in their place. In that manner heat which would otherwise be wasted is usefully employed to bring the objects to be heated part way up to the desired temperature.

Heating current is supplied by suitable heavy copper conductors 33, 34, connected to a suitablesource of energy, such as a transformer 35. The connection of the electrodes 12-16 to secondary winding 36 is shown in Fig. 6. i

In the apparatus above described a heating load consisting, for example, ofrivcts the handles 39 pivotally attached to the right 5 and provided with an insulat ng pad. 1 0 a l. the-region of contact with the corre-" supports, this being conveniently done by sponding electrode. The object of the recess in each of the lateral supports is to enable the weight of the electrodes to be exerted upon the objects being heated without resting on the supports 811, so as to insure a firm butt contact whenv a suitable heating current is supplied by the transformer. The series connected rivets are gradually brought up to the desired temperature unitormly throughout their length. parently the ballasting effect of each of the objects in the series upon each other prevents local overheating as the drop of potential must remain distributed and connot pile up at one particular region of poor contact which would become overheated were a single object placed between the terminals ol a transformer. There is also a reactive ballasting et'l'ect, caused largely by the current path being surrounded by metal, each of the electrodes 8 to 11 being inat'erially larger than the objects being heated. When one of the rivets in the series is sulliciently heated it is replaced by a cold rivet. the heat in the rest being distributed during the intervening interval. The current is again applied, and when another rivet has been fully heated .it in turn is replaced by a cold rivet. Each increment of current causes-one ot' the rivets in the series to attain its. desired high temperature while the rivet most recently inserted is given its first heating, which in 'the ordinary opera tion of the device does not usually bring it up to visible redness. \Vhen the rivets which have become fully heated are removed they should be with-- drawn without:- releasing the Weight oi the electrodes thereby tending to clean the electrodes at the point of contact. In some cases when some scale or other insulating material has accumulatedon the electrodes or theends ot the objects to be heated are not bright. it may be necessary to tap the upper electrode in order to make a better contact, but it ordinary care is exercised during the operation of the device and a suitable voltage impressed upon the series, no dilliculty will be experienced.

The described device may be used For various heat treating and tempering opera lions.

hat I claim as new and desire to secure by Letters Patent ot the l nited States, is z l. The method oi l ating objects such as bolts and rivets having an imperfect contact surface, which consists in applying butt. contacts to a plurality ot said objects. ap

tudinally through a plurality of said objects connected electrically in series with each other, dissipating heat generated at 'the contacting ends of said objects, and. successively replacing objects having attained a desired temperature by unheated objects.

3. The method of heating elongated ob jects, such as bolts and rivets, which consists in periodically passing an electric heating current through a plurality of said objects in series and successively replacing be-' tween periods of current input objects in said series which hr 0. attained a desired. temperature with unheated objects thereby causing each object to be subjected to more than one period of current input.

4. A metal heating device comprising a pair of electrodes, one or more bodies having good electrical\and heat conductivity located intermediate said electrodes and adapted to complete an electri -al circuit between a plurality of objects to be heated held respectively between the same and said electrodes.

A metal heating device comprising a frame, a series of electrodes adapted to receive objects to be heated, supported at spaced intervals on said frame, means for conducting a heating current to the outermost electrodes at opposite ends of said series and insulating means for supporting said electrodes when not supported by the objects to be heated.

(i. A device for heating rivets and the like haiiug imperfectv contact surfaces, comprising 11 plurality of electrodes between which the articles to be heated are adapted to be interposed, and means for supplying a. curren in series through said electrodes and interposed articles.

7. An apparatus for heating rivets and the like comprising a stationa electrode, a plurality of movable electrodes constructed and arranged so that the articles to be electrically heated may be interposed between said electrodes and a transftn'mcr winding connected to supply current in series through a plurality of said electrodes and' the articles interposed therebet-Ween.

In witness whereof I have hereunto set my hand this 24th day of April, 1918.

HENRY GEESEHH ONEH. 

